Telephone system.



c. L. GOODRUM! TELEPHONE SYSTEM.

APPLICATION FILED ram-29.19:].

1,2034. v Patented Oct. s, 1918.

' T D STATESPATENTOFFICE.

snare-Lust. eoonauiu, or New YORK, N. 48 mm T0 WESTERN ELECTRIC COM- 1 ANY,-INCORPORA'1'E,D, or NEW. YORK, n; A'com ona'rrori OF NEW YORK.

' To all whom it may concern :Be it known'that 1, CHARLES L'. GoonRUM, a citizen of :the United States, residing at New York, in the'county of New York and State of New York, haveinvented certain new anduseful Improvements in Telephone Systems, of which the folltwingjs aufull,

clear, concise, and exact description,

v This invention relates to improvements in telephone systems, and more particularly to improvements in systems employing machine switching.

It is well known that the magneto tele phone receiver transmits voice currents with clearness and accuracy, and without the distortion which arises when the microphone is employed as part of the telephone equipment. However, when the .magneto telephone recei'ver'is employed to generate voice.

currents, these currents. are so minute that the diaphragm of the receiver of the listenin'g party is actuated so gently that the message is scarcely audible. As regards transmission, the useof the magneto telephone is particularly advantageous, since the voice currents are so minute that difliculty from crosstalk is minimized and conductors of a much smaller size may be employed? 1 In order to utilize the magneto telephone receiver in the transmission of-the voice curcated in this disclosure, and may be of any desired construction. The portion of Fig. 1, included within the dotted line inclosure,

represents the so-called mechanical re-.

peater and a'circuit arrangement associated therewith, which cooperates therewith to amplify the voice currents transmitted over the established connection.

Fig. 2 diagrammatically represents a modified form of the invention in which a vacuum tuberelay of the audion type is modified instead of the peatcr. When the apparatus and circuits,

Specification of Letters Patent. Application filed March 29, 1917. I Serial No. 153,198.

mechanical rernnnrnonn sYsrnm.

, Patented Oct. s, 1918.

shown 2, are substituted for the correspondlng elements, included within the dotted. line inclosure of Fig. 1, the arrange-.

Inent'by which a vacuum tube relay may be employed to amplify voice currents in an audion telephone system, will be shown.

The substation'set' employed in this system consists of'a dial switch 1 of any preferred form, and a combined transmitter and receiver. This combined transmitter and receiver is provided with a permanent magnet'2, near one end of which there is provided-a coil in se'riesnwith the talking cir cuit. -Thi's permanent magnet operates in the well-known manner to actuate a diaphragm 3. The subscriber speaks into the mouthpieceA and actuates the-diaphragm 3,

nals'16, 17 and 18 of the calling line. The

operation of the line finder serves to extend the calling line to an idle first selector and in turn to the proper connector. As soon as the calling line has been extended to the connector, the line relay 32 is energized over a circuit extending from battery, left-hand winding of relay 32, terminal 29, brush 23 of the selector, brush 13 and terminal 16 of the line finder, contacts of the substation impulse sender 1, through the substation circuit, terminal 17 and brush 14 of the line finder, brush 24 and terminal 30 of theselector, right-hand winding of relay 32, back to battery. The line relay 32 attracts its armature and completes an energizing circuit for the slow-releasing relay 33, which circuit is traceable from grounded battery, winding of relay 33, front contact and armature of relay 32, to ground. It will be understood that the relay-33 is slow to release and therefore does not retract its armatures during momentary interruptions 54 of the switch is opened. In response to armature and front contact of relay 33, conductor 35, side-switch wiper 36 in its first position, winding of primary stepping magnet 34, to grounded battery. In response to the tens series of impulses, the connector switch operates to place its brushes 37, 38 and 39 opposite the group of lines in which the called line terminates. As soon as the relay 33 attracted its armature and upon the first retraction of relay 32 a circuit was completed from ground, armature and back contact of relay 32, right-hand front contact and armature of relay 33, Winding of slow-releasing relay 40, to grounded battery. The relay 40 attracts its armaturesand at its right-hand armature and contact completes an energizing circuit for escape magnet 41, Wl'llOl'l circuit is completed from grounded battery, winding of relay 41, right-handfront contact and armature of relay 40,'back contact and armature of ringing trip relay 42, to ground. The escape magnet 41 is energized in this circuit.

At the close of the tens series of impulses, the line relay 32 attracts its armature for a relatively long interval which interrupts at its armature and back contact the operating circuit of the relay 40 for a sufliciently long period to permit this relay to deenergize. Upon the deenergization of the relay 40 the escape magnet 41 deenergizes and moves the side-switch Wipers into their second position.

position, conductor 35, right-hand front.

contact and armature of relay 33, back con- "tact and armature of line relay 32, to

net 41 to attract its armatures.

signaling current 51. signaling currentis applied to the calling into engagement with the terminals 44, 45 and 46 of the called line.

If the called line is idle when the relay 40 retracts its armatures, the energizing circuit of the escape magnet 41 is interrupted, causing this magnet to move the side-switch wipers into their third position. In position 3 of the side-switch wipers the relay 40 is energized over a circuit traceable from grounded battery, winding of relay 40, conductor 35, side-switch wiper 36, in its third position, conductors 47 and 62, front-contact and armature of relay '32, to ground. Relay 4O in energizing causes escape mag- A circuit is now completed from grounded battery, winding of relay 40, conductor 35, side-switch wiper 36 in its third position, conductor 47, side-switch wiper 48, connector brush 37, and-terminal 44' of the called line, through the substation circuit at B, terminal 45 of the called line, connector brush 38, sideswitch wiper 49 in its third position, conductor 50, armature and front contact of escape magnet 41, winding of a ringing trip relay 42, to the source of high-frequency The high-frequency line and operates the diaphragm of the receiver in the same manner as a bowler.

When the called subscriber at the substation removes his receiver from its switchhook, the ringing trip relay 42, which-is marginal, is energized and at its armature and back contact interrupts the energizing circuit of the escape magnet 41 to move the side-switch wipers into their fourth or talkmg posltion.

When the side-switch wipers 58, 59. 60 and 61 are moved into their fourth position, a current amplifier, which may be of the type disclosed in the patent to Colpitts, No. 1,200,082,, October 3, 1916. is connected to the talking trunk which interconnects the calling and called substations.

The primary winding 7 of the. repeater coil 8 is bridged across the conductors of the trunk interconnecting the substations A and B. The secondary winding of the repeater coil 8 leads. to the actuating Winding 10 of a telephone repeater of the receiver microphone type. Telephonic currents, therefore, coming in from a telephone station A over the selected trunk will flow through the winding 10 of the repeater and actuate the microphone elements 12, thereby sending out amplifying telephone currents through the windings 21 of the output transformer 20, Whose secondary windings are included in series with the conductors of the trunk leading to the substation B.

v If, however, the desired line is busy as a called line, ground will be applied to the test terminal 46 through a side-switch wiper similar to 52 in its fourth position through 7. In a telephone system, an incoming line,

a plurality of outgoing-lines, an automatic switch for interconnecting said incoming line with any of said outgoinglines, means associated with said incoming line and with each of said outgoing lines for generating and receiving voice currents, and a thermionic amplifier for amplifying said voice cur rents, said amplifier being connected to said incoming line.

8. In a telephone system, an incoming line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any of said'outgoing lines to ex tend a talking circuit, means associated. with said incoming line and with each of said thermionic amplifier being connected to said talking circuit by said automatic switch ,in its operation.

l0.- In a telephone exchange system, an incoming line, a plurality of outgoing lines, an automatic swltch for interconnecting said incoming line with any of said outgoing lines to extend a talking circuit, said automatic switch being provided with anauxiliary switch, means associated with said incoming line and with each of said outgoing l lines for generating and receiving voice currents, and a thermionic amplifier for amplifying said voice currents, said thermionic amplifier being connected to said talking circuit by said auxiliary switch.

11. In a telephone system, a telephone exchange, an incoming line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any of said outgoing lines, means associated with said'incoming line and with each of said outgoing lines for generating and receiving voice currents, and a thermionic amplifier at said telephone eichange for amplifying said voice currents.

12. In a telephone system, a telephone ex change, an incoming line, a plurality of outgoinglines, an automatic switch for interconnecting said inconjng line with any of said outgoing lines to extend a talking circuit, means associated with said incoming line and wlth each of said outgoing llnes for generating and receiving voice currents, and

a thermionic amplifier at said telephone exchange for amplifying said voice currents, said thermionic amplifier being connected to said talking circuit.

\ 13. In a telephone system, a telephone exchange, n incoming line, a plurality of out going lines, an automatic'switch for interconnecting said incoming line with any of said outgoing lines to extend a talking circuit, means associated with said incoming line and with each of said outgoing lines for generating and receiving voice currents, and a thermionic amplifier at said telephone exchange for amplifying said voice currents,

said thermionic amplifier being connectedto -said talking circuit by said automatic switch in its operation.

14. In a telephone system, subscribers lines each provided with a device for receiving and transmitting voice currents, automatic means for interconnecting said subscribers lines, and means common to a plurality of said lines for amplifying said voice currents.

15. In a telephone system, subscribers lines each provided with a device of constant impedance for receiving and transmittingvoice currents, automatic means for interconnecting said subscribers lines, and

. means common to a plurality of said lines for amplifying said voice currents.

16. In a telephone system, subscribers lines each provided with device having constant electrical characteristics for receiving and transmitting voice currents, automatic meansfor interconnecting said subscribers lines, and means common to a plurality of said lines for amplifying said voice currents.

In witness whereof, I hereunto subscribe my name this 27th day of March, A. D. 1917.

CHARLES L. GOODRUM. 

